It is known in the art to build machines for cleaning floors and similar surfaces. These are commonly sweepers or scrubbers, and some provide both functions. We are concerned here with a scrubber, or with the scrubbing elements of a combined sweeper-scrubber.
A floor scrubber operates by applying a solution of water and detergent to the floor, scrubbing with one or more brushes to separate soilage from the floor and suspend it in the solution, then removing the soiled solution from the floor with a vacuum squeegee located behind the brushes. The floor is left damp-dry and soon dries completely, which is important for safety reasons because people can slip and fall on a wet floor.
For this same reason it is important that the machine does not leave puddles of water anywhere. This becomes a consideration when the machine turns, because in sharp turns the side component of machine motion causes the water path coming from the brushes to travel sideways and the rear squeegee will not completely cover it. This leaves a puddle or wet streak on the floor.
Side squeegees have been developed to cope with this problem. These commonly have a single rubber lip pressed against the floor, are placed on either side of the brushes and are generally parallel to the straight travel direction of the machine. In length they extend from about the front of the brushes to somewhat behind them, and their rear ends are often curved inward to better direct water to the rear squeegee, especially in turns. They effectively control the water on the floor in straight travel and in turns if the radius of turn is not too short. They have been used on scrubbers having two rear wheels and one or two steerable front wheels and in which the scrub brushes are mounted close to the rear axle line, either in front of it or behind it. Those vehicle configurations subject the brushes and squeegees to only moderate side motion in a turn, and side squeegees control the water adequately if the flow of water to the floor is reduced before going into a turn. There may be some wet streaking if the water flow is not reduced.
A vehicle layout having two front wheels and a single steerable rear wheel which may also be powered has advantages in some cases, particularly for accommodating the sweeping elements of a combination sweeper-scrubber. A single powered steerable wheel can be turned almost 90 degrees, so very sharp turns are possible. However, in such a turn the rear end of the machine swings almost completely sideways, taking with it any components near the rear wheel, which include the scrub brushes and squeegees. Side squeegees mounted as discussed earlier are not able to control the water on the floor during such extreme side motion, even if the flow of water to the floor is reduced. Water will flow outward past the leading end of the trailing side squeegee, leaving an unacceptable puddle or streak of water on the floor. The leading side squeegee will be subject to abnormal wear due to being "rolled under." This may cause it to interfere with the adjacent scrub brush, which will abrade it severely.
One effort to improve the action of side squeegees on a rear steered scrubber is disclosed in U.S. Pat. No. 4,158,901. Its concept is to couple the side squeegees to the vehicle steering system with a cam and cable arrangement such that both side squeegees are held off the floor during straight travel, and one or the other of them is lowered to the floor during a turn, the one on the inside of the turn being the one that is lowered. This would eliminate the abnormal wear on the leading squeegee, but appears to do nothing for water control. There is still a need for effective side squeegees on a rear steered scrubber.